3.5 Nucleic Acids
4 min read•june 14, 2024
Nucleic acids are the building blocks of life, storing and transmitting genetic information. and , composed of , play crucial roles in cellular processes. Their structures and functions are essential for understanding how organisms inherit traits and produce proteins.
DNA's double helix structure ensures accurate replication and information transfer. RNA's diverse forms, including , , and , facilitate protein synthesis and gene regulation. Understanding nucleic acids is key to grasping the fundamentals of genetics and molecular biology.
Nucleic Acids
Components of nucleic acids
Top images from around the web for Components of nucleic acids
Structure and Function of DNA | Microbiology View original
Is this image relevant?
DNA Structure – Principles of Biology View original
Is this image relevant?
Nucleic Acids – Principles of Biology View original
Is this image relevant?
Structure and Function of DNA | Microbiology View original
Is this image relevant?
DNA Structure – Principles of Biology View original
Is this image relevant?
1 of 3
Top images from around the web for Components of nucleic acids
Structure and Function of DNA | Microbiology View original
Is this image relevant?
DNA Structure – Principles of Biology View original
Is this image relevant?
Nucleic Acids – Principles of Biology View original
Is this image relevant?
Structure and Function of DNA | Microbiology View original
Is this image relevant?
DNA Structure – Principles of Biology View original
Is this image relevant?
1 of 3
- Nucleotides serve as the fundamental building blocks of nucleic acids
- provides structural support and negative charge
- forms the backbone of the nucleic acid strand
- sugar present in DNA (lacks hydroxyl group on 2' carbon)
- sugar found in RNA (retains hydroxyl group on 2' carbon)
- determines the identity and pairing properties of the nucleotide
- consist of a double-ringed structure (fused pyrimidine and imidazole rings)
- (A) pairs with (T) in DNA or (U) in RNA
- (G) pairs with (C) in both DNA and RNA
- have a single-ringed structure
- Cytosine (C) pairs with guanine (G) in both DNA and RNA
- Thymine (T) found exclusively in DNA, pairs with adenine (A)
- Uracil (U) replaces thymine in RNA, pairs with adenine (A)
- consist of a double-ringed structure (fused pyrimidine and imidazole rings)
- Two main types of nucleic acids play crucial roles in cellular processes
- stores and transmits genetic information
- structure provides stability and protection
- Serves as the blueprint for protein synthesis and inheritance
- participates in various cellular functions
- Single-stranded structure allows for diverse roles and interactions
- Acts as an intermediary in gene expression and regulation (mRNA, tRNA, rRNA)
- stores and transmits genetic information
DNA structure for genetic storage
- DNA adopts a double helix structure, consisting of two polynucleotide strands
- Strands run in opposite directions (5' to 3' and 3' to 5')
- form between complementary base pairs, stabilizing the structure
- Adenine (A) pairs with thymine (T) via two hydrogen bonds
- Guanine (G) pairs with cytosine (C) through three hydrogen bonds
- provides structural support and connects nucleotides
- Adjacent nucleotides are joined by bonds
- ensures accurate replication and information transfer
- Each strand serves as a template for the synthesis of a new complementary strand
- maintains genetic integrity across generations
- DNA stores genetic information in the sequence of its nucleotides
- are specific segments of DNA that encode proteins or functional RNA molecules
- The order of nucleotides determines the amino acid sequence of the encoded protein
- The complete set of genetic material in an organism is called the
- Genetic information is passed from parent to offspring, ensuring continuity of life
RNA structure vs cellular roles
- RNA has a single-stranded polynucleotide structure, differing from DNA in several ways
- Shorter in length compared to DNA molecules
- Contains ribose sugar instead of deoxyribose (hydroxyl group on 2' carbon)
- Uracil (U) replaces thymine (T) as the complementary base to adenine (A)
- Can fold into diverse secondary structures (hairpins, loops) due to base pairing
- RNA molecules play various roles in cellular processes, depending on their type
- acts as a template for protein synthesis
- Produced through , carrying genetic information from DNA to
- (triplets of nucleotides) specify the amino acid sequence of the protein
- serves as an adapter molecule in protein synthesis
- on tRNA base pairs with the codon on mRNA
- Delivers specific amino acids to the ribosome during
- forms the structural and catalytic core of ribosomes
- Assists in the assembly and function of ribosomes during protein synthesis
- Catalyzes the formation of peptide bonds between amino acids
- Small nuclear RNA () participates in the splicing of pre-mRNA
- Removes introns and joins exons to produce mature mRNA
- Ensures proper gene expression and protein diversity
- MicroRNA () and small interfering RNA () regulate gene expression
- Bind to complementary sequences on target mRNA molecules
- Inhibit translation or promote degradation of mRNA, fine-tuning protein levels
- acts as a template for protein synthesis
Nucleic Acid Metabolism and Information Flow
- Nucleases are enzymes that cleave the phosphodiester bonds between nucleotides
- Play crucial roles in DNA repair, replication, and RNA processing
- Nucleosides are precursor molecules consisting of a nitrogenous base and a sugar
- Serve as building blocks for nucleotides and nucleic acids
- The describes the flow of genetic information in biological systems
- DNA is transcribed into RNA, which is then translated into proteins
- interactions contribute to the stability of nucleic acid structures
- Occur between adjacent base pairs in the DNA double helix
Key Terms to Review (52)
Adenine: Adenine is one of the four primary nitrogenous bases found in DNA and RNA, specifically classified as a purine. It plays a crucial role in the storage and transfer of genetic information and energy in cells. In nucleic acids, adenine pairs with thymine in DNA and uracil in RNA, forming the rungs of the molecular ladder that composes the double helix structure.
Aminoacyl tRNA synthetases: Aminoacyl tRNA synthetases are enzymes that attach the correct amino acid to its corresponding tRNA molecule during protein synthesis. They play a crucial role in translating genetic information into functional proteins.
Anticodon: An anticodon is a sequence of three nucleotides in transfer RNA (tRNA) that corresponds to a complementary codon in messenger RNA (mRNA). This pairing is crucial for the accurate translation of genetic information into proteins, as the anticodon ensures that the correct amino acid is added to the growing polypeptide chain during protein synthesis. The interaction between anticodons and codons underpins the genetic code and is essential for ribosomal function.
Antiparallel: Antiparallel refers to the arrangement of two parallel structures in opposite orientations. In the context of nucleic acids, particularly DNA, it describes how the two strands of the double helix run in opposite directions, allowing for complementary base pairing and proper functioning during processes like replication. This structural feature is critical for maintaining the integrity and functionality of genetic information.
Base Stacking: Base stacking refers to the stabilizing interactions between adjacent nucleotide bases in a nucleic acid structure, primarily DNA and RNA. These interactions occur through hydrophobic forces and van der Waals forces, which contribute significantly to the overall stability of the double helix structure. Base stacking plays a crucial role in maintaining the integrity of nucleic acids, impacting their function, replication, and overall shape.
Central dogma: The central dogma is a fundamental principle in molecular biology that describes the flow of genetic information within a biological system. It outlines how DNA is transcribed into RNA, which is then translated into proteins, forming the basis for gene expression and function in living organisms. This concept has shaped our understanding of molecular genetics and the mechanisms underlying heredity and evolution.
Codons: Codons are sequences of three nucleotides in messenger RNA (mRNA) that specify a particular amino acid or a stop signal during protein synthesis. These triplet sequences are crucial for translating the genetic code into functional proteins, linking nucleic acids to the world of proteins. Each codon corresponds to a specific amino acid or signals the termination of translation, playing an essential role in determining the structure and function of proteins.
Complementary base pairing: Complementary base pairing is the specific hydrogen bonding between nucleotide bases in DNA and RNA, where adenine pairs with thymine (or uracil in RNA) and cytosine pairs with guanine. This pairing is crucial for maintaining the double helical structure of DNA, ensuring accurate replication, and facilitating the process of transcription. By forming stable bonds between complementary bases, this mechanism supports genetic fidelity and proper gene expression.
Complementary DNA (cDNA) libraries: cDNA libraries are collections of complementary DNA (cDNA) sequences synthesized from mRNA templates. They are used to study gene expression and identify coding regions in genomics research.
Cytosine: Cytosine is one of the four primary nitrogenous bases found in nucleic acids, specifically DNA and RNA. It pairs with guanine through three hydrogen bonds in DNA, playing a critical role in the structure and function of genetic material, as well as the processes of transcription and replication.
Deoxyribonucleic acid (DNA): Deoxyribonucleic acid (DNA) is a molecule that carries genetic information essential for the growth, development, functioning, and reproduction of all living organisms. It consists of two strands that coil around each other to form a double helix.
Deoxyribose: Deoxyribose is a five-carbon sugar that is a crucial component of DNA (deoxyribonucleic acid), forming part of its backbone along with phosphate groups. This sugar distinguishes DNA from RNA (ribonucleic acid) by lacking one oxygen atom, which affects the stability and structure of the nucleic acids. The absence of this oxygen atom in deoxyribose contributes to the double-helix structure of DNA and plays an important role in the genetic coding and information storage within living organisms.
Dideoxynucleotides: Dideoxynucleotides are modified nucleotides lacking a 3' hydroxyl group, which prevents the addition of further nucleotides during DNA synthesis. They are essential components in Sanger sequencing for terminating DNA strand elongation at specific bases.
DNA: DNA, or deoxyribonucleic acid, is the hereditary material in nearly all living organisms, encoding the genetic instructions that govern the development, functioning, growth, and reproduction of cells. This molecule is central to many biological processes, linking the concepts of genetic inheritance to molecular biology and the chemistry of life.
Double-stranded helix: A double-stranded helix is a molecular structure formed by two strands of nucleotides that twist around each other, resembling a spiral staircase. This arrangement is most famously associated with DNA, where the two strands are held together by complementary base pairing and stabilized by hydrogen bonds. The double-stranded nature of this structure is crucial for its stability and function in storing genetic information and facilitating replication.
Five-carbon sugar: A five-carbon sugar, also known as pentose, is a type of carbohydrate that contains five carbon atoms in its molecular structure. These sugars play a crucial role in the formation of nucleotides, which are the building blocks of nucleic acids like DNA and RNA. The two main types of five-carbon sugars are ribose and deoxyribose, each differing slightly in their structure and function within nucleic acids.
Genes: Genes are segments of DNA that serve as the basic units of heredity, determining the traits and characteristics of an organism. They encode the information necessary for producing proteins, which play critical roles in cellular functions and overall development. Each gene can influence multiple traits, and their interactions contribute to the genetic variation observed within populations.
Genome: A genome is the complete set of genetic material within an organism, including all of its genes and non-coding sequences. It serves as the blueprint for the development, functioning, and reproduction of that organism. Understanding genomes is crucial for studying heredity, evolutionary biology, and various disorders, as well as for the fields of genomics and proteomics that explore gene functions and interactions.
Guanine: Guanine is one of the four primary nitrogenous bases found in nucleic acids, specifically DNA and RNA. It plays a critical role in the storage and transmission of genetic information and pairs with cytosine in the structure of DNA, contributing to the double helix's stability. This base is essential for protein synthesis and other cellular functions, making it a vital component in the molecular biology of all living organisms.
Hydrogen Bonds: Hydrogen bonds are weak interactions that occur between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom. These bonds play a crucial role in stabilizing the structure of nucleic acids, particularly DNA, by forming connections between complementary base pairs, which is essential for the integrity and function of genetic material.
Messenger RNA (mRNA): Messenger RNA (mRNA) is a single-stranded molecule that carries genetic information from DNA to the ribosome, where proteins are synthesized. It serves as a template for translating genetic code into amino acids, forming proteins.
MiRNA: miRNA, or microRNA, is a small non-coding RNA molecule, typically 20 to 22 nucleotides long, that plays a crucial role in the regulation of gene expression by targeting messenger RNA (mRNA) for degradation or inhibiting its translation. These molecules are key players in post-transcriptional regulation, influencing various biological processes such as development, differentiation, and cellular responses to stress.
MRNA: mRNA, or messenger RNA, is a single-stranded molecule that carries genetic information from DNA to the ribosome, where proteins are synthesized. This process is essential for translating the genetic code into functional proteins, connecting it to various cellular processes and regulation mechanisms.
Nitrogenous Base: A nitrogenous base is a molecular component of nucleic acids that contains nitrogen and acts as a fundamental building block for DNA and RNA. These bases are essential for encoding genetic information, pairing through hydrogen bonds, and contributing to the overall structure of nucleic acids. In DNA, there are four primary nitrogenous bases—adenine, thymine, cytosine, and guanine—while RNA contains adenine, uracil, cytosine, and guanine.
Nuclease: A nuclease is an enzyme that catalyzes the hydrolysis of nucleic acids, breaking down DNA or RNA into smaller components such as nucleotides. Nucleases play crucial roles in various biological processes including DNA repair, replication, and degradation, making them vital for cellular function and genetic integrity.
Nucleoside: A nucleoside is a molecular structure that consists of a nitrogenous base bonded to a sugar molecule, specifically ribose or deoxyribose. This combination is crucial because nucleosides serve as the building blocks of nucleotides, which are the essential components of nucleic acids like DNA and RNA. Understanding nucleosides is key to grasping how genetic information is stored and transmitted in living organisms.
Nucleotides: Nucleotides are the building blocks of nucleic acids, consisting of a nitrogenous base, a five-carbon sugar, and one or more phosphate groups. They play a crucial role in various biological processes, such as energy transfer, cellular signaling, and the synthesis of DNA and RNA.
Phosphate group: A phosphate group is a molecular group consisting of one phosphorus atom bonded to four oxygen atoms, typically represented as -PO₄. This functional group is crucial in biological molecules, particularly in the formation of nucleic acids and energy-carrying molecules, making it essential for life processes.
Phosphodiester: Phosphodiester bonds are covalent chemical bonds that link the 3' carbon atom of one sugar molecule to the 5' carbon atom of another in a nucleic acid. These bonds form the backbone of DNA and RNA molecules, providing structural integrity.
Phosphodiester bond: A phosphodiester bond is a chemical linkage that forms the backbone of nucleic acids like DNA and RNA, connecting the 5' phosphate group of one nucleotide to the 3' hydroxyl group of another. This type of bond is crucial for the structural integrity and stability of nucleic acids, allowing them to store and transmit genetic information effectively.
Post-transcriptional: Post-transcriptional regulation refers to the control of gene expression at the RNA level, after transcription has occurred. This can include processes such as RNA splicing, editing, transport, and degradation.
Post-translational: Post-translational refers to modifications made to a protein after it has been synthesized in a cell. These changes can affect the protein’s function, localization, stability, or interactions with other molecules.
Purines: Purines are a type of nitrogenous base found in nucleic acids, characterized by a two-ring structure. The most common purines in DNA and RNA are adenine (A) and guanine (G).
Purines: Purines are a type of nitrogenous base that are fundamental components of nucleotides, which in turn are the building blocks of nucleic acids like DNA and RNA. They play a critical role in various biological processes including energy transfer, signaling, and the synthesis of nucleic acids. Purines include adenine and guanine, which pair with specific pyrimidines in the structure of nucleic acids, contributing to genetic information storage and transmission.
Pyrimidines: Pyrimidines are a class of nitrogenous bases that play a crucial role in the structure of nucleic acids, specifically DNA and RNA. These single-ring structures include cytosine, thymine, and uracil, which are essential for encoding genetic information and supporting cellular functions. Pyrimidines pair with purines in the formation of nucleotides, contributing to the stability and integrity of nucleic acid structures.
Restriction endonucleases: Restriction endonucleases are enzymes that cut DNA at specific nucleotide sequences, known as restriction sites. They are essential tools in molecular cloning, genetic mapping, and various DNA manipulation techniques.
Ribonucleic acid (RNA): Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles, including coding, decoding, regulation, and expression of genes. It is typically single-stranded and composed of ribonucleotides linked by phosphodiester bonds.
Ribose: Ribose is a five-carbon sugar that is a crucial component of nucleotides, which are the building blocks of nucleic acids such as RNA. It plays an essential role in cellular metabolism and energy transfer, particularly as part of ATP (adenosine triphosphate), the primary energy carrier in cells. Ribose is also involved in the synthesis of nucleotides that are fundamental for the production of RNA, linking it to genetic expression and cellular functions.
Ribosomal RNA (rRNA): Ribosomal RNA (rRNA) is a type of RNA that combines with proteins to form ribosomes. These ribosomes are the cellular structures where protein synthesis occurs.
Ribosomes: Ribosomes are molecular machines within cells responsible for synthesizing proteins by translating messenger RNA (mRNA) sequences into polypeptide chains. These essential structures link amino acids together in the order specified by the mRNA, making them crucial for the synthesis of biological macromolecules like proteins, which play various roles in cellular functions and structures.
RNA: RNA, or ribonucleic acid, is a nucleic acid molecule essential for various biological roles, particularly in coding, decoding, regulation, and expression of genes. It serves as a crucial intermediary between DNA and proteins, playing key roles in protein synthesis and gene regulation, ultimately impacting cellular function and organismal development.
RRNA: Ribosomal RNA (rRNA) is a type of non-coding RNA that is a fundamental component of ribosomes, which are the cellular structures responsible for protein synthesis. rRNA molecules provide structural support and catalyze the chemical reactions involved in translating messenger RNA (mRNA) into proteins. This makes rRNA crucial for cellular function and gene expression, linking it closely to the processes of transcription and translation.
Semiconservative replication: Semiconservative replication is the process by which DNA makes copies of itself, where each new double helix consists of one original strand and one newly synthesized strand. This method ensures that the genetic information is preserved through generations, allowing for accurate transmission of hereditary traits.
SiRNA: siRNA, or small interfering RNA, is a class of double-stranded RNA molecules that play a crucial role in the regulation of gene expression through a process called RNA interference (RNAi). This mechanism involves the silencing of specific genes by degrading their corresponding mRNA, preventing the translation of those genes into proteins. siRNA is essential for maintaining cellular functions and has applications in genomics and proteomics for studying gene functions and therapeutic interventions.
SnRNA: snRNA, or small nuclear RNA, is a class of RNA molecules found within the nucleus of eukaryotic cells, primarily involved in the splicing of pre-mRNA. These small RNA molecules play a critical role in the removal of introns and the joining of exons during the maturation of messenger RNA, facilitating accurate gene expression. Their function is essential for producing functional proteins from the genetic code.
Sugar-phosphate backbone: The sugar-phosphate backbone is a structural framework of nucleic acids, consisting of alternating sugar and phosphate groups. This backbone provides stability and support for the attached nitrogenous bases, which carry the genetic information in DNA and RNA. The arrangement of these components is crucial for the formation of nucleotides and the overall structure of DNA during processes like replication.
Thymine: Thymine is one of the four nucleotide bases found in DNA, represented by the letter 'T'. It pairs with adenine (A) through two hydrogen bonds, forming the rungs of the DNA ladder structure. Thymine's presence is critical for the stability and integrity of DNA, influencing processes such as base pairing during DNA replication.
Transcription: Transcription is the biological process where the DNA sequence of a gene is copied into RNA. This process is essential for gene expression, as it allows the genetic information stored in DNA to be transferred to messenger RNA (mRNA), which then guides protein synthesis. It serves as the first step in expressing genes, linking the genetic code found in DNA to the production of proteins necessary for cellular functions.
Transfer RNA (tRNA): Transfer RNA (tRNA) is a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. It functions by carrying specific amino acids to the ribosome during protein synthesis.
Translation: Translation is the biological process by which proteins are synthesized from messenger RNA (mRNA) templates. This process involves decoding the mRNA sequence into a specific sequence of amino acids, which are the building blocks of proteins, and occurs in the ribosomes, where transfer RNA (tRNA) brings amino acids to the growing polypeptide chain. Translation connects the genetic code carried by mRNA to functional proteins, playing a crucial role in gene expression and cellular function.
TRNA: tRNA, or transfer RNA, is a type of RNA molecule that plays a crucial role in protein synthesis by transporting specific amino acids to the ribosome during translation. It acts as an adapter, matching its anticodon with the corresponding codon on the mRNA strand, ensuring that the correct amino acid is added to the growing polypeptide chain. This process is essential for translating the genetic information encoded in DNA into functional proteins.
Uracil: Uracil is a nitrogenous base that is one of the four main building blocks of RNA, replacing thymine found in DNA. It plays a crucial role in coding, decoding, and regulating genes, linking to protein synthesis and various cellular processes.